The use of cylinder locks in connection with various pieces of equipment, such as furniture, automobiles and the like is well known. Various forms of such cylinder locks have been constructed for diverse applications, the configuration of any particular cylinder lock employed being a function of the equipment or other environment in which the lock is utilized.
It is further known that in some applications, the equipment in which the lock is installed is necessarily constructed with the locking mechanisms contained interiorally within the equipment. Hence, once the equipment is fully constructed, having the entire lock mechanism self-contained therein, it quite often develops that the keyed cylinder portion of the lock is similarly contained within the equipment exposing only the key slot. Hence, should any difficulties arise in connection with the operation of the portion of the lock operated by a bitted key, it is often necessary to dismantle the equipment in order to gain access to repair the lock. Even more importantly, should the consumer or user of the equipment wish to re-key the cylinder portion of the lock such that the lock will be operated by a different key, it is similarly necessary to dismantle the equipment in order to gain access to the cylinder portion of the lock. This in true, for example, in connection with commercial desks and other office equipment, which include drawers having a lock mechanism associated therewith, which permits the user thereof to actuate the lock mechanism in order to lock all of the drawers in a closed position. In the past, desks or other office equipment incorporating such lock mechanisms have been constructed with the locking levers which effect the locking function being totally enclosed within the confines of the equipment, the only portion of the lock mechanism accessible to the user being the keyed portion which presents the keyed slot to the user. In this, as well as other applications, it became apparent that it would be necessary to have a cylinder lock wherein the lock core portion of the lock could be removed from the cylinder housing in order to permit the lock core to be replaced, re-keyed, or to repair any damage. To this end, various constructions of removable lock cores have been developed with a view toward permitting the independent removal of the lock core portion of the lock from the cylinder housing.
Typically, cylinder locks having a removable lock core have been developed wherein the lock core is usually removable by means of a special release key which is intended to operate a special release tumbler once the lock is manipulated into a certain position by the locking key. The release key will not operate the lock and can only be used in the release position to remove the lock core. Hence, the release key functions only for the purpose of lock core removal, and does not operate the lock in any respect. In addition, in order to accommodate this type of construction, the cylinder housing is usually grooved in a special manner which will permit the lock core to be rotated and yet, retained within the housing in any rotational position with the exception of one rotational position wherein the special release tumbler can then be manipulated by the release key to ride into a particularly shaped grooved formed in the interior wall of the cylindrical housing. In this manner, lock core removal may be effected.
A cylinder lock exemplary of the construction mentioned above is shown in U.S. Pat. No. 2,061,456 which shows a cylinder lock having a removable lock core associated therewith. As is shown in the drawings, the cylindrical housing includes a pair of opposed grooves formed in the housing wall which are intended to coact with the release tumbler contained within the lock core. One of the grooves is shown to be wider than the other groove, and the release tumbler has an upper portion which corresponds only with the wider groove. The design is such that the lock core cannot be removed from the cylindrical housing unless and until the lock core is rotatably manipulated such that the release tumbler is in registry with the wider groove. In this position, when the release key is inserted, it will actuate the release tumbler into a retracted position into the wider groove permitting the lock core to be withdrawn.
Similarly, in U.S. Pat. No. 2,460,709, the cylindrical housing in which the removable lock core is contained is designed with a specially constructed groove to accommodate the sixth tumbler formed in the lock core. The sixth tumbler functions as the release tumbler and alternated between a locked position, and a release position. The lock core can only be removed when the sixth tumbler is aligned properly such that the release tumbler is actuated to the release position where it will ride in an appropriately shaped groove formed in the cylindrical housing and permit removal of the lock core.
The above-mentioned prior art patents, as well as various others not specifically mentioned, all have certain basic features in common. In particular, one such feature is that the release tumbler which controls the locking position and the release position of the lock core relative to the cylindrical housing is a specially constructed tumbler, usually having a wider disc portion associated therewith, the release tumbler coacts with an appropriately formed groove in the interior wall of the cylindrical housing. It will be appreciated, therefore, that in order to manufacture cylindrical locks of this type, it is necessary that the cylindrical housings be specially grooved during the manufacturing process to accommodate the release tumbler which controls the lock and release positions of the lock core. This requires a separate manufacturing step in order to properly groove the interior walls of the cylindrical housing, after which the interior portions of the cylindrical housing must be deburred. In addition, it will be appreciated that a specially constructed release tumbler must be utilized which is different than the lock tumblers normally contained along the length of the lock core. This adds a further manufacturing expense to the production costs involved in producing a cylindrical lock having a removable lock core.
Finally, it is noted that with all prior art locks having a removable lock core, the lock core itself is uniformly constructed along the length thereof. This construction is predicated upon the fact that the cylinder housings in such prior art locks generally have a ledge along which the release tumbler will ride during its locked position, and also are provided with the specially formed groove in the interior surface of the housing which accommodates the positioning of the release tumbler when actuated by the release key in order to permit lock core removal.
In accordance with the present invention, the cylindrical housing and lock core have been reconstructed and redesigned in a manner which permits positive steps for the rotational movement of the lock core when contained within the cylindrical housing, while eliminating the need for any special grooves to be formed within the interior confines of the cylindrical housing in order to accommodate a removable lock core.